A round Mark point positioning method based on connected region filtering relates to positioning methods. The round Mark point positioning method based on the connected region filtering mainly solves the problem that traditional round Mark point positioning methods are complex in positioning algorithm, high in computer memory requirements, low in detecting time, low in detecting accuracy and prone to being affected by external environments to lead to template matching failure, meanwhile, have high Mark process requirements and cannot meet the detecting accuracy requirements for deformed round Mark points. The method comprises firstly, calculating the ROI (region of interest) of a target Mark point; secondly, obtaining the edge of the target point; thirdly, obtaining a binary ROI image; fourthly, retaining the ROI connected region with the maximum area; fifthly, retaining the ROI background connected region with the maximum area; sixthly, designing a noise filter; seventhly, obtaining filtering Canny edge points; eighthly, obtaining the minimum enclosing rectangle; ninthly, removing Canny edge defects; lastly, obtaining the central and radial parameters of the round Mark point. The round Mark point positioning method based on the connected region filtering is applied to the field of positioning methods.